A process and apparatus can be used to vacuum skin package a product arranged on a support comprising providing a film portion above said support with the product being arranged between the support and the film portion; air tightly fixing the film portion to the support; removing at least a portion of air from a volume underneath said film portion through said at one nozzle inserted in an interspace between the film portion and the support.
|
1. A vacuum skin packaging process comprising:
providing a support comprising an indent formed therein;
providing a film;
loading the support with a product, such that the product leaves a free surface of the support not contacted by the product;
holding a film portion above the product loaded support in a holding position;
inserting a nozzle into the indent and in an interspace between an upper surface of the support and a bottom surface of the film portion;
heating the film portion;
evacuating air from below the film portion by sucking gas through a suction aperture of the nozzle;
releasing the held film portion; and
allowing the released film portion to contact the product and heat bond to the free surface of the support, the heat bonding forming an air-tight closure of the product between the support and the film portion thereby forming a vacuum skin packaged product;
wherein the nozzle is kept in the indent and the interspace while heat bonding is taking place, such that at least one film flap is formed where the nozzle is kept during heat bonding, wherein the at least one film flap is located above the indent and is not heat bonded to the support, thereby forming a grip element for opening of the vacuum skin packaged product.
2. The process of
3. The process of
4. The process of
the heating the film portion takes place by action of a heater, carried by or forming an upper tool, while the film portion is in its holding position above the respective product loaded support,
the releasing the film portion from the upper tool takes place after approaching the upper tool and a lower tool and bringing the film portion in contact with the support,
after the step of releasing, at least part of the heated film portion separates and moves away from the heater draping down onto the product.
5. The process of
the upper tool comprises a recess configured for receiving the nozzle, the nozzle cross section presenting a profile counter-shaped to a profile of the upper tool recess, and
when the nozzle is inserted in the interspace, the nozzle is located, in the recess present in the upper tool.
6. The process of
7. The process of
8. The process according to
9. The process of
10. The process of
11. The process of
12. The process of
13. The process of
a flange or a top portion of the side wall of the tray comprises the indent configured to receive the nozzle, the nozzle cross section presenting a profile counter-shaped to a profile of the indent; and
when the nozzle is inserted in the interspace, the nozzle is located in the indent present in the tray.
|
|||||||||||||||||||||||||||||||
The present invention generally relates to an apparatus and to a process for vacuum skin packaging of a product.
Vacuum packaging is a well-known process for packaging a wide variety of products, in particular food products. Among the known vacuum packaging processes, vacuum skin packaging is employed for packaging food products such as fresh and frozen meat and fish, cheese, processed meat, ready meals and the like.
Vacuum skin packaging is basically a thermoforming process. In particular, the product is placed on a rigid or semi-rigid support (such as a tray, a bowl, a plate, or a cup). The support with the product placed thereon is put in a vacuum chamber, where a film of thermoplastic material, held above the product placed on the support, is heated and softened. The space between the support and the film is then evacuated and finally the film is released to cause the film to drape down all around the product forming a tight skin around the product and on the support.
In order to improve the removal of air from a tray during vacuum skin packaging, it is known to form a hole in the tray side wall, as disclosed in EP 0320294. Trays with pre-manufactured holes are known also from DE102006022418, U.S. Pat. No. 4,919,955, WO9714313 and US2005074531. It should however be noted that formation of holes in the tray implies a certain burden in the production chain. Moreover, the position or size of the holes or venting channels present on the tray may not be always optimized to the specific packaging machine. Additionally, the presence of holes on the tray walls causes an undesirable aesthetic perception of the overall packaging. Furthermore, in connection with the holes present on the trays disclosed in DE102006022418, U.S. Pat. No. 4,919,955 and US2005074531 valve means are provided which therefore further complicate the tray structure.
DE102006022418 also discloses an alternative where a mobile snorkel in inserted between the tray flange and the bottom surface of the closure film: in a suction position, the snorkel extends above the flange and beyond an inner border of the flange. A sealing body operative above the closure film and the flange heats the film to fix it to the tray flange substantially along the perimeter of the flange with the exception of an unsealed flange area located where the snorkel is inserted between flange and film. When the snorkel moves away from the tray flange, a further mobile heater intervenes on the portion of closure film overlapping said unsealed flange area to heat seal it to the same flange. This solution requires an additional heater which shall be properly moved and synchronized with the movement of the snorkel, causing added complexity to the apparatus. Moreover, the vacuum level that can be reached is compromised by the necessity to leave a portion of the film unsealed for at least a short time interval. WO2009141214 and WO2014060507 disclose a method for vacuum skin packaging wherein a hole is formed in the tray before removing air from the tray through said hole. This method allows to effectively obtain vacuum skin packaged products, although it requires the additional step of forming the hole in a tray wall.
It is therefore an object of the present invention to provide an apparatus and a process capable of adequately solving the problem of efficient air removal during a vacuum skin process, without impairing in term of complexity of the production cycle.
Moreover, it is an auxiliary object providing a process and an apparatus which are capable of efficiently remove air from a wide variety of trays or supports during vacuum skin packaging.
Additionally, it is an object providing a process and an apparatus which may be implemented with no need of complex changes to conventional packaging systems.
Another auxiliary object is an apparatus capable of operating in a safe manner.
A further auxiliary object is an apparatus and a process capable of achieving the goal of air removal without impairing on the aesthetics of the final packaged product.
Another object of the invention is a new package having a design allowing efficient air removal and improving the aesthetic perception of the package.
At least one of the above objects is substantially reached by an apparatus and by a process according to one or more of the appended claims.
Apparatus and processes according to aspects of the invention and capable of achieving one or more of the above objects are here below described.
A 1st aspect concerns a—preferably vacuum skin—packaging process comprising the steps of:
The free surface of the support, in the case where the support is a tray with a bottom wall, a side wall and a top flange, may include the top surface of the flange only, or the top surface of the flange and part of the inner surface of the side wall of the tray, or the top surface of the flange and part of the inner surface of the side wall of the tray.
In a 2nd aspect according to the first aspect the process is a vacuum skin packaging process wherein the film portion is adhered to the product exposed surface and sealed to the support leaving minimum quantity of gas inside the packaging.
In a 3rd aspect according to any one of the preceding aspects the process comprises the following step:
In a 4th aspect according to any one of the preceding aspects the process comprises the following further step:
In a 5th aspect according to any one of the preceding aspects the at least one nozzle (80) is inserted between an upper surface of a peripheral border of the support (7) and a lower surface of a peripheral border of the film portion (33) such that the suction aperture of the nozzle (80) is directed towards a volume comprised between the support (7) and the film portion (33); and then air is evacuated from said volume by sucking gas through said suction aperture.
In a 6th aspect according to any one of the preceding aspects, the process provides that—after loading the product (P) on the support (7)—the product loaded support (7) is positioned in a packaging assembly comprising at least a lower tool (52) and an upper tool (51), wherein holding the at least one film portion (33) comprises holding by the upper tool (51) said film portion (33) in its holding position above the respective product loaded support (7) hosted in the lower tool (52).
In a 7th aspect according to the preceding aspect the process comprises a step of approaching to each other the upper and lower tools to bring the film portion (33) in contact with the support (7) before evacuating air from below the same film portion.
In an 8th aspect according to the 6th aspect the process comprises a step of approaching to each other the upper and lower tools to form a closed, preferably hermetically closed, packaging chamber (58) and evacuating air takes place after the upper and lower tools have formed the closed packaging chamber (58).
In a 9th aspect according to any one of the preceding aspects the step of evacuating air takes place also while the film portion (33) is in its holding position above the respective product loaded support (7) and continues after releasing the film portion (33) and until formation of said heat bonding which tightly closes the product (P) between the support (7) and the film portion (33).
In a 10th aspects according to the 8th and 9th aspects the step of evacuating air takes place also while the film portion (33) is in its holding position above and at a distance from the respective product loaded support (7).
In a 11th aspect according to any one of the preceding aspects, the process provides that air evacuation take place only through said at least one nozzle (80) and only when the film portion (33) has been brought into sealing contact with a peripheral border or band of the underlying support forming a sealing contact with the support (7) and with a portion of the side surface of the nozzle (80) inserted in the interspace (90). In practice, the film portion is first contacting the support (for instance the peripheral flange of the support or a peripheral band of the support) and the side surface of the nozzle (this latter being located in said interspace) to form an annular contact region which is not leaking gas surrounding the suction aperture or apertures of the nozzle(s) which thus serves as sole passage 8s) for suction of gas from the volume between the film portion and the support. Note that the formation of said annular contact region is facilitated by the action of the upper and lower tools which are basically sandwiching the film portion and the support with the nozzle(s) located at the respective interspace.
In a 12th aspect according to any one of the preceding aspects from 6th to 11th:
In a 13th aspect according to any one of the preceding aspects from 6th to 12th:
In a 14th aspect according to any one of the preceding aspects from 6th to 13th:
In a 15th aspect according to any one of the preceding aspects, the nozzle (80) is kept in said interspace (90) between the film portion (33) and the support (7) while said heat bonding step is taking place, such that at least one film flap (33a) is formed, which is located above said interspace (90) and which does not heat bond to the underlying support (7), thereby forming a grip element for easy opening of the skin package.
In a 16th aspect according to the preceding aspect the nozzle (80) is removed, in particular completely removed, from said interspace (90) after either one or both of the following occurs:
In a 17th aspect according to any one of the preceding aspects, after the step of allowing the film portion (33) to contact the product (P) and heat bond to a free surface of the support (7) surrounding the product (P), the film portion (33) comprises an inner film portion (34), which is in contact with the product (P), and an outer film portion (35), entirely surrounding the perimeter of the inner film portion (33) and heat bonded to the free surface support (7) not covered by the product (P) in such a manner to form an heat bonding band also entirely surrounding the perimeter of the inner film portion (33).
In a 18th aspect according to any one of the preceding aspects, after the step of allowing the film portion (33) to contact the product (P) and heat bond to a free surface of the support (7) surrounding the product (P), the process comprises:
In a 19th aspect according to any one of the preceding aspects, the step of removing the nozzle (80) from said interspace (90) comprises extracting the nozzle (80) from said interspace (90).
In a 20th aspect according to the preceding aspect, the extracting of the nozzle (80) begins before interrupting suction of gas through said nozzle (80) such that the nozzle (80) continues to suck air at least during an initial phase of its extraction from the interspace (90).
In a 21st aspect according to any one of the preceding aspects, said support (7) is a tray comprising a bottom wall (7a) and a side wall (7b) upwardly extending from said bottom wall (7a) and wherein said film portion (33) is heat bonded to a free surface of the side wall (7b) of the tray and forms the heat bonding.
In a 22nd aspect according to the preceding aspect the heat bonding is a heat bonding band extending all around the product (P) and all around the side wall (7b).
In a 23rd aspect according to any one of the preceding two aspects the tray comprises a top flange (7c) extending radially outside from the side wall (7b) upper portion and said interspace (90) is defined between an upper surface of the tray flange (7c) and a lower surface of the film portion (33), said film portion (33) being bonded to upper surface of the flange (7c) along the entire perimeter of the flange (7c) with the exception of a zone of the flange (7c) located at said interspace (90), to form at least one film flap (33a) not heat bonded to the underlying flange (7c).
In a 24th aspect according to the preceding aspect the at least one nozzle (80) is inserted between an upper surface of the tray flange (7c) and a lower surface of a peripheral border of the film portion (33) and does not extend beyond the inner border of the tray flange (7c).
In a 25th aspect according to any one of the preceding two aspects the film portion (33) is held in contact with the heater (54) of the upper tool (51), optionally by vacuum, also while said film portion (33) is being positioned above the product loaded tray and while the film portion (33) is being placed into contact with the flange (7c) of the tray.
In a 26th aspect according to any one of the preceding aspects the support (7) has a polygonal peripheral border and the nozzle (80) is positioned in an interspace (90) defined at a corner region of the support (7) peripheral border between the upper surface of the support (7) and the bottom surface of the film portion (33).
In a 27th aspect according to the preceding aspect the support (7) is a tray with a side wall (7b) and a radially protruding top flange (7c) and the peripheral border of the flange (7c) is polygonal and the nozzle (80) is positioned in the interspace (90) defined at a corner region of the flange (7c) peripheral border between the upper surface of the flange (7c) and the bottom surface of the film portion (33).
In a 28th aspect according to any one of the preceding aspects the film portion (33) is a discrete piece of film substantially having—when hold in its holding position above the product loaded support—a size covering substantially all the support top surface, optionally having the size capable of covering substantially all the top surface of the tray flange (7c).
In a 29th aspect according to any one of the preceding aspects the flange (7c) or the top portion of the side wall (7b) of the tray comprises an indent (7d) configured for receiving said nozzle (80), the nozzle (80) cross section presenting a profile counter-shaped to the profile of the indent (7d), optionally wherein the indent (7d) is located at a corner region of the tray.
In a 29th aspect according to any one of the preceding aspects the upper tool (51) comprises a recess configured for receiving said nozzle (80), the nozzle (80) cross section presenting a profile counter-shaped to the profile of the upper tool (51) recess.
In a 30th aspect according to any one of the preceding two aspects the nozzle (80) inserted in said interspace (90) is located either in the indent (7d) present in the tray or in the recess present in the upper tool (51) or in both.
A 31st aspect concerns an apparatus (1) for packaging a product (P) arranged on a support (7).
In a 32nd aspect according to the preceding aspect the apparatus is configured to implement the process according to any one of the preceding aspects.
In a 33rd aspect according to any one of the preceding two aspects the apparatus is configured for the vacuum skin packaging of a product on said support (7) which is either a flat support or which is a tray having a base wall (7a) and side wall (7b).
In a 34th aspect according to any one of the preceding aspects from the 31st to the 33rd said apparatus (1) comprises:
In a 35th aspect according to the preceding aspect the control unit is also configured for commanding the packaging assembly to:
In a 36th aspect according to the preceding aspect the packaging assembly comprises:
In a 37th aspect according to the preceding aspect the lower tool (52) and the upper tool (51) are configured to position the film portion (33) in a holding position above the respective support (7), and wherein the nozzle (80) is mounted in the packaging assembly (5) for relative movement with respect to said upper and lower tools between a working condition—where the nozzle (80) is inserted in said interspace (90)—and a rest condition—where the nozzle (80) is extracted from the interspace (90) and positioned at a prefixed distance from the peripheral border of the support (7) present in the lower tool (52).
In a 38th aspect according to any one of the preceding four aspects the control unit (100) is configured to command the packaging assembly (5) to:
In a 39th aspect according to any one of the preceding five aspects the control unit (100) is configured to command the packaging assembly (5) to:
In a 40th aspect according to any one of the preceding two aspects the control unit (100) is configured to command the packaging assembly (5) to:
In a 41st aspect according to the preceding aspect the control unit (100) is configured to command the packaging assembly (5) to—contemporaneously to or after at least an initial phase of air evacuation—release the film portion (33) such that at least a part of the film portion (33) separates from the heater (54) and contacts the product (P) while heat bonding to a free surface of the support (7) surrounding the product (P), and then remove the nozzle (80) from said interspace (90) by relatively displacing the nozzle (80) with respect to lower tool (52) and thus with respect to the support (7) present in the lower tool (52).
In a 42nd aspect according to any one of the preceding four aspects the control unit (100) is further configured to command the upper and lower tools to form an hermetically closed packaging chamber (58) before commanding the vacuum arrangement (82) to cause evacuation of air.
In a 43rd aspect according to any one of the aspects from the 34th to the 42nd the control unit (100) is configured to: command the heater (54) to heat the film portion (33) while the same film portion (33) is in its holding position above the support (7); and
cause the nozzle (80) to be removed, in particular completely removed, from said interspace (90) only after the heat bonding has air-tightly closed the product (P) between the support (7) and the film portion (33).
In a 44th aspect according to any one of the aspects from the 34th to the 43rd the control unit (100) is configured for commanding the packaging assembly to:
maintain the nozzle (80) in said interspace (90) between the film portion (33) and the support (7) at least until after either one or both of the following occurs:
In a 45th aspect according to any one of the aspects from the 34th to the 44th the control unit (100) is configured to:
In a 46th aspect according to the preceding aspect the control unit (100) is configured to command said relative displacement of the nozzle (80) to begin before interrupting suction of gas through said nozzle (80) such that the nozzle (80) continues to suck air at least during an initial phase of its extraction from the interspace (90).
In a 47th aspect according to any one of the aspects from the 34th to the 46th the lower tool (52) is configured for receiving a support (7) in the shape of a tray comprising a bottom wall (7a), a side wall (7b) upwardly extending from said bottom wall (7a), and an optional top flange (7c) extending radially outside from the side wall (7b) upper portion and wherein the control unit (100) is configured to command the packaging assembly to position the nozzle (80) in the working condition in the interspace (90) defined between a lower surface of the film portion (33) hold by the upper tool (51) and the flange (7c) upper surface or the upper portion of the side wall (7b) of a tray positioned in the lower tool (52).
In a 48th aspect according to the preceding aspect the control unit (100) is configured to command the packaging assembly (5) to position the nozzle (80) in the working condition to radially extend beyond an outer border of the tray flange (7c) but not to radially extend beyond an inner border of the same tray flange (7c) of a tray positioned in said lower tool (52).
In a 49th aspect according to any one of the aspects from the 34th to the 48th the control unit (100) is configured to command holding means (59) associated to the upper tool (51) to hold the film portion (33) in contact with a heating surface of a heater (54) carried by the upper tool (51) while said film portion (33) is being positioned above the support (7) hosted in the lower tool (52).
In a 50th aspect according to the preceding aspect the holding means (59) comprises a plurality of suction apertures leading to the active surface of the heater (54) and at least one vacuum source (59b) controlled by the control unit (100) and connected to the suction apertures, the control unit (100) being configured for commanding the vacuum source (59b) to keep the film portion (33) in contact with said suction apertures until the film portion peripheral border has contacted the flange (7c) of the tray.
In a 51st aspect according to any one of the aspects from the 34th to the 50th the lower tool (52) is configured to receive a support (7) having a polygonal peripheral border and wherein the control unit (100) is configured to command the packaging assembly (5) to position the nozzle (80) in the working condition in an interspace (90) defined at a corner region of the peripheral border of the tray (7) positioned in the lower tool (52).
In a 52nd aspect according to any one of the aspects from the 34th to the 51st the film supply assembly (3) is configured for supplying a continuous film (31); and the apparatus further comprises a cutting unit (4) configured to form the film portion (33) as a discrete piece of film cut from the continuous film and substantially having the radial size of the support (7), optionally having the radial size of the tray flange (7c); said cutting unit being operative outside the packaging assembly at a cutting station located between the film supply assembly and the packaging assembly or said cutting unit being part of the packaging assembly and being carried by the upper and/or lower tool (51, 52).
In a 53rd aspect according to any one of the aspects from the 34th to the 52nd the lower tool (52) is configured for receiving a support (7) in the shape of a tray comprising a bottom wall (7a), a side wall (7b) upwardly extending from said bottom wall (7a) and an optional top flange (7c) extending radially outside from the side wall (7b) upper portion of the flange (7c), with said flange (7c) or the top portion of the side wall (7b) of the tray comprising an indent (7d) configured for receiving said nozzle (80),
the nozzle (80) cross section presenting a profile counter-shaped to the profile of the indent (7d), optionally wherein the indent (7d) is located at a corner region of the tray.
In a 54th aspect according to any one of the aspects from the 34th to the 53rd the upper tool (51) comprises a recess configured for receiving said nozzle (80), the nozzle (80) cross section presenting a profile counter-shaped to the profile of the upper tool (51) recess.
In a 55th aspect according to any one of the preceding two aspects the control unit (100) is configured to command the packaging assembly to position the nozzle (80) in said interspace (90) either in correspondence of the indent (7d) present in the tray or in correspondence of the recess present in the upper tool (51).
In a 56th aspect according to any one of the preceding aspects the nozzle (80) or at least an external coating applied to the nozzle (80) is made in non-stick material. The non-stick material is in particular selected not to stick to heated plastic films of the type disclosed in the detailed description when heated to bond to the support.
In a 57th aspect according to any one of the preceding aspects the nozzle (80) cross section presents elongated conformation and is preferably polygonal, for example rectangular, further wherein the nozzle (80) suction aperture optionally comprises a plurality of suction orifices regularly distributed at the distal end of the nozzle (80).
A 58th aspect concerns a vacuum skin package, for instance of the type obtainable with the process of any one of the preceding aspects comprising:
In a 59th aspect according to the preceding aspect the indent (7d) is located at a corner region of the flange or of the sidewall.
In a 60th aspect according to any one of the preceding two aspects the tray (7) comprises the top flange (7a) extending radially outside from the side wall upper portion and provided with said indent (7d).
In a 61st aspect according to any one of the preceding three aspects said film portion (33) is bonded to upper surface of the flange (7c) along the entire perimeter of the flange with the exception of a zone of the flange where the indent (7d) is formed to define at least one film flap (33a) not heat bonded to the underlying flange (7c).
In a 62nd aspect according to any one of the preceding four aspects the indent (7d) in the flange and the film flap (33a) are located at said flange corner region.
In a 63rd aspect according to any one of the preceding five aspects the indent (7d) is formed by a reduction in the height of the side wall (7c), has a constant depth and an extension along the perimeter of the flange or of the side wall which is at least twice the depth of the indent.
In a 64th aspect according to any one of the preceding six aspects the film portion (33) comprises an inner film portion (34), which is in contact with the product (P), and an outer film portion (35), entirely surrounding the perimeter of the inner film portion and heat bonded to the free surface of the support not covered by the product in such a manner to define an annular heat bonding band (91) also entirely surrounding the perimeter of the inner film portion and encircling the area or areas of contact of the product with the support.
In a 65th aspect according to the preceding aspect the annular heat bonding band (91) extends up to the top border of the side wall, and optionally covers the flange (7c) with the exclusion of the zone of said indent (7d).
In a 66th aspect according to any one of the preceding eight aspects the indent (7d) and/or the flap (33a) are delimited on both sides by a distinct sealing line connecting the film to the flange and extending transverse to the external peripheral border of the flange.
In a 67th aspect according to any one of the preceding aspects from the 58th to the 65th the indent (7d) and/or the flap (33a) are delimited between the external border of the corner region of the flange and a single sealing line crossing the corner region of the flange tangentially with respect to the side wall of the tray.
Aspects of the present invention are disclosed in the following detailed description, which is provided by way of example and should not be read in a limitative manner.
The description makes reference to the accompanying drawings, wherein:
As used herein support means a flat or substantially flat support or a container of the type having a base wall, a side wall and optionally a top flange radially emerging from the side wall; the support or tray may be made either in plastic material or in cardboard or in one or more cardboard layers combined with one or more plastic layers.
The tray or supports may have a polygonal, e.g., rectangular, shape (when seen from above) or any other suitable shape, such as round, square, elliptical and other.
Trays or supports with a side wall may for example be manufactured by thermoforming or injection molding. Tray or supports of flat conformation may be extruded, co-extruded, laminated and then the cut to size.
The trays or supports described and claimed herein are preferably, although not limited to, made of a single layer or of a multi-layer polymeric material.
In case of a single layer material suitable polymers are for instance polystyrene, polypropylene, polyesters, high density polyethylene, poly(lactic acid), PVC and the like, either formed or solid.
Preferably the tray or support is provided with gas barrier properties. As used herein such term refers to a film or sheet of material which has an oxygen transmission rate of less than 200 cm3/m2-day-bar, less than 150 cm3/m2-day-bar, less than 100 cm3/m2-day-bar as measured according to ASTM D-3985 at 23° C. and 0% relative humidity. Suitable materials for gas barrier monolayer thermoplastic trays 4 are for instance polyesters, polyamides and the like.
If the tray or support is made of a multi-layer polymeric material, suitable polymers are for instance ethylene homo- and co-polymers, propylene homo- and co-polymers, polyamides, polystyrene, polyesters, poly(lactic acid), PVC and the like. Part of the multi-layer material can be solid and part can be foamed.
For example, the tray or support may comprises at least one layer of a foamed polymeric material chosen from the group consisting of polystyrene, polypropylene, polyesters and the like.
The multi-layer material may be produced either by co-extrusion of all the layers using co-extrusion techniques or by glue- or heat-lamination of, for instance, a rigid foamed or solid substrate with a thin film, usually called “liner”. The thin film may be laminated either on the side of the tray or support 4 in contact with the product P or on the side facing away from the product P or on both sides. In the latter case the films laminated on the two sides of the tray or support may be the same or different. A layer of an oxygen barrier material, for instance (ethylene-co-vinyl alcohol) copolymer, is optionally present to increase the shelf-life of the packaged product P.
Gas barrier polymers that may be employed for the gas barrier layer are PVDC, EVOH, polyamides, polyesters and blends thereof. The thickness of the gas barrier layer will be set in order to provide the tray with an oxygen transmission rate suitable for the specific packaged product.
The tray or support may also comprise a heat sealable layer. Generally, the heat-sealable layer will be selected among the polyolefins, such as ethylene homo- or co-polymers, propylene homo- or co-polymers, ethylene/vinyl acetate copolymers, ionomers, and the homo- and co-polyesters, e.g. PETG, a glycol-modified polyethylene terephthalate.
Additional layers, such as adhesive layers, to better adhere the gas-barrier layer to the adjacent layers, may be present in the gas barrier material for the tray and are preferably present depending in particular on the specific resins used for the gas barrier layer.
In case of a multilayer material used to form the tray or support, part of this structure may be foamed and part may be un-foamed. For instance, the tray or support may comprise (from the outermost layer to the innermost food-contact layer) one or more structural layers, typically of a material such as foam polystyrene, foam polyester or foam polypropylene, or a cast sheet of e.g. polypropylene, polystyrene, poly(vinyl chloride), polyester or cardboard; a gas barrier layer and a heat-sealable layer.
The tray or support may be obtained from a sheet of foamed polymeric material having a film comprising at least one oxygen barrier layer and at least one surface sealing layer laminated onto the side facing the packaged product, so that the surface sealing layer of the film is the food contact layer the tray. A second film, either barrier or non-barrier, may be laminated on the outer surface of the tray.
Specific tray or support formulations are used for food products which require heating in conventional or microwave oven before consumption. The surface of the container in contact with the product, i.e. the surface involved in the formation of the seal with the lidding film, comprises a polyester resin. For instance the container can be made of a cardboard coated with a polyester or it can be integrally made of a polyester resin. Examples of suitable containers for the package of the invention are CPET, APET or APET/CPET containers. Such container can be either foamed or not-foamed.
Trays or supports containing foamed parts, have a total thickness lower than 8 mm, and for instance may be comprised between 0.5 mm and 7.0 mm and more frequently between 1.0 mm and 6.0 mm.
In case of rigid tray not containing foamed parts, the total thickness of the single-layer or multi-layer thermoplastic material is preferably lower than 2 mm, and for instance may be comprised between 0.1 mm and 1.2 mm and more frequently between 0.2 mm and 1.0 mm.
The Film or Film Material
The film or film material described and claimed herein may be applied to the tray or support 4 to form a skin associated to the tray and matching the contour of the product.
The film for skin applications may be made of a flexible multi-layer material comprising at least a first outer heat-sealable layer, an optional gas barrier layer and a second outer heat-resistant layer. The outer heat-sealable layer may comprise a polymer capable of welding to the inner surface of the supports carrying the products to be packaged, such as for instance ethylene homo- or co-polymers, like LDPE, ethylene/alpha-olefin copolymers, ethylene/acrylic acid copolymers, ethylene/methacrylic acid copolymers, and ethylene/vinyl acetate copolymers, ionomers, co-polyesters, e.g. PETG. The optional gas barrier layer preferably comprises oxygen impermeable resins like PVDC, EVOH, polyamides and blends of EVOH and polyamides. The outer heat-resistant layer may be made of ethylene homo- or copolymers, ethylene/cyclic-olefin copolymers, such as ethylene/norbornene copolymers, propylene homo- or co-polymers, ionomers, (co)polyesters, (co)polyamides. The film may also comprise other layers such as adhesive layers or bulk layers to increase thickness of the film and improve its abuse and deep drawn properties. Particularly used bulk layers are ionomers, ethylene/vinyl acetate copolymers, polyamides and polyesters. In all the film layers, the polymer components may contain appropriate amounts of additives normally included in such compositions. Some of these additives are preferably included in the outer layers or in one of the outer layers, while some others are preferably added to inner layers. These additives include slip and anti-block agents such as talc, waxes, silica, and the like, antioxidants, stabilizers, plasticizers, fillers, pigments and dyes, cross-linking inhibitors, cross-linking enhancers, UV absorbers, odor absorbers, oxygen scavengers, bactericides, antistatic agents and the like additives known to those skilled in the art of packaging films.
One or more layers of the film can be cross-linked to improve the strength of the film and/or its heat resistance. Cross-linking may be achieved by using chemical additives or by subjecting the film layers to an energetic radiation treatment. The films for skin packaging are typically manufactured in order to show low shrink when heated during the packaging cycle. Those films usually shrink less than 15% at 160° C., more frequently lower than 10%, even more frequently lower than 8% in both the longitudinal and transversal direction (ASTM D2732). The films usually have a thickness comprised between 20 microns and 200 microns, more frequently between 40 and 180 microns and even more frequently between 50 microns and 150 microns.
In all the film layers herein described, the polymer components may contain appropriate amounts of additives normally included in such compositions. Some of these additives are preferably included in the outer layers or in one of the outer layers, while some others are preferably added to inner layers. These additives include slip and anti-block agents such as talc, waxes, silica, and the like, antioxidants, stabilizers, plasticizers, fillers, pigments and dyes, cross-linking inhibitors, cross-linking enhancers, UV absorbers, odor absorbers, oxygen scavengers, bactericides, antistatic agents, anti-fog agents or compositions, and the like additives known to those skilled in the art of packaging films.
PVDC is any vinylidene chloride copolymers wherein a major amount of the copolymer comprises vinylidene chloride and a minor amount of the copolymer comprises one or more unsaturated monomers copolymerisable therewith, typically vinyl chloride, and alkyl acrylates or methacrylates (e.g. methyl acrylate or methacrylate) and the blends thereof in different proportions. Generally a PVDC barrier layer will contain plasticisers and/or stabilizers as known in the art.
As used herein, the term EVOH includes saponified or hydrolyzed ethylene-vinyl acetate copolymers, and refers to ethylene/vinyl alcohol copolymers having an ethylene comonomer content preferably comprised from about 28 to about 48 mole %, more preferably, from about 32 to about 44 mole % ethylene, and even more preferably, and a saponification degree of at least 85%, preferably at least 90%.
The term “polyamides” as used herein is intended to refer to both homo- and co- or ter-polyamides. This term specifically includes aliphatic polyamides or co-polyamides, e.g., polyamide 6, polyamide 11, polyamide 12, polyamide 66, polyamide 69, polyamide 610, polyamide 612, copolyamide 6/9, copolyamide 6/10, copolyamide 6/12, copolyamide 6/66, copolyamide 6/69, aromatic and partially aromatic polyamides or co-polyamides, such as polyamide 6I, polyamide 6I/6T, polyamide MXD6, polyamide MXD6/MXDI, and blends thereof.
As used herein, the term “copolymer” refers to a polymer derived from two or more types of monomers, and includes terpolymers. Ethylene homopolymers include high density polyethylene (HDPE) and low density polyethylene (LDPE). Ethylene copolymers include ethylene/alpha-olefin copolymers and ethylene/unsaturated ester copolymers. Ethylene/alpha-olefin copolymers generally include copolymers of ethylene and one or more comonomers selected from alpha-olefins having from 3 to 20 carbon atoms, such as 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene and the like.
Ethylene/alpha-olefin copolymers generally have a density in the range of from about 0.86 to about 0.94 g/cm3. The term linear low density polyethylene (LLDPE) is generally understood to include that group of ethylene/alpha-olefin copolymers which fall into the density range of about 0.915 to about 0.94 g/cm3 and particularly about 0.915 to about 0.925 g/cm3. Sometimes linear polyethylene in the density range from about 0.926 to about 0.94 g/cm3 is referred to as linear medium density polyethylene (LMDPE). Lower density ethylene/alpha-olefin copolymers may be referred to as very low density polyethylene (VLDPE) and ultra-low density polyethylene (ULDPE). Ethylene/alpha-olefin copolymers may be obtained by either heterogeneous or homogeneous polymerization processes.
Another useful ethylene copolymer is an ethylene/unsaturated ester copolymer, which is the copolymer of ethylene and one or more unsaturated ester monomers. Useful unsaturated esters include vinyl esters of aliphatic carboxylic acids, where the esters have from 4 to 12 carbon atoms, such as vinyl acetate, and alkyl esters of acrylic or methacrylic acid, where the esters have from 4 to 12 carbon atoms.
Ionomers are copolymers of an ethylene and an unsaturated monocarboxylic acid having the carboxylic acid neutralized by a metal ion, such as zinc or, preferably, sodium.
Useful propylene copolymers include propylene/ethylene copolymers, which are copolymers of propylene and ethylene having a majority weight percent content of propylene, and propylene/ethylene/butene terpolymers, which are copolymers of propylene, ethylene and 1-butene.
As used herein, the term “polyolefin” refers to any polymerized olefin, which can be linear, branched, cyclic, aliphatic, aromatic, substituted, or unsubstituted. More specifically, included in the term polyolefin are homopolymers of olefin, co-polymers of olefin, co-polymers of an olefin and a non-olefinic co-monomer co-polymerizable with the olefin, such as vinyl monomers, modified polymers thereof, and the like. Specific examples include polyethylene homo-polymer, polypropylene homo-polymer, polybutene homo-polymer, ethylene-alpha-olefin co-polymer, propylene-alpha-olefin co-polymer, butene-alpha-olefin co-polymer, ethylene-unsaturated ester co-polymer, ethylene-unsaturated acid co-polymer, (e.g. ethylene-ethyl acrylate co-polymer, ethylene-butyl acrylate co-polymer, ethylene-methyl acrylate co-polymer, ethylene-acrylic acid co-polymer, and ethylene-methacrylic acid co-polymer), ethylene-vinyl acetate copolymer, ionomer resin, polymethylpentene, etc.
The term “polyester” is used herein to refer to both homo- and co-polyesters, wherein homo-polyesters are defined as polymers obtained from the condensation of one dicarboxylic acid with one diol and co-polyesters are defined as polymers obtained from the condensation of one or more dicarboxylic acids with one or more diols. Suitable polyester resins are, for instance, polyesters of ethylene glycol and terephthalic acid, i.e. poly(ethylene terephthalate) (PET). Preference is given to polyesters which contain ethylene units and include, based on the dicarboxylate units, at least 90 mol %, more preferably at least 95 mol %, of terephthalate units. The remaining monomer units are selected from other dicarboxylic acids or diols. Suitable other aromatic dicarboxylic acids are preferably isophthalic acid, phthalic acid, 2,5-, 2,6- or 2,7-naphthalenedicarboxylic acid. Of the cycloaliphatic dicarboxylic acids, mention should be made of cyclohexanedicarboxylic acids (in particular cyclohexane-1,4-dicarboxylic acid). Of the aliphatic dicarboxylic acids, the (C3-Ci9)alkanedioic acids are particularly suitable, in particular succinic acid, sebacic acid, adipic acid, azelaic acid, suberic acid or pimelic acid. Suitable diols are, for example aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-butane diol, 1,4-butane diol, 1,5-pentane diol, 2,2-dimethyl-1,3-propane diol, neopentyl glycol and 1,6-hexane diol, and cycloaliphatic diols such as 1,4-cyclohexanedimethanol and 1,4-cyclohexane diol, optionally heteroatom-containing diols having one or more rings.
Co-polyester resins derived from one or more dicarboxylic acid(s) or their lower alkyl (up to 14 carbon atoms) diesters with one or more glycol(s), particularly an aliphatic or cycloaliphatic glycol may also be used as the polyester resins for the base film. Suitable dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, or 2,5-, 2,6- or 2,7-naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as succinic acid, sebacic acid, adipic acid, azelaic acid, suberic acid or pimelic acid. Suitable glycol(s) include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-butane diol, 1,4-butane diol, 1,5-pentane diol, 2,2-dimethyl-1,3-propane diol, neopentyl glycol and 1,6-hexane diol, and cycloaliphatic diols such as 1,4-cyclohexanedimethanol and 1,4-cyclohexane diol. Examples of such copolyesters are (i) copolyesters of azelaic acid and terephthalic acid with an aliphatic glycol, preferably ethylene glycol; (ii) copolyesters of adipic acid and terephthalic acid with an aliphatic glycol, preferably ethylene glycol; and (iii) copolyesters of sebacic acid and terephthalic acid with an aliphatic glycol, preferably butylene glycol; (iv) co-polyesters of ethylene glycol, terephthalic acid and isophthalic acid. Suitable amorphous co-polyesters are those derived from an aliphatic diol and a cycloaliphatic diol with one or more, dicarboxylic acid(s), preferably an aromatic dicarboxylic acid. Typical amorphous copolyesters include co-polyesters of terephthalic acid with an aliphatic diol and a cycloaliphatic diol, especially ethylene glycol and 1,4-cyclohexanedimethanol.
It should be noted that in the present detailed description corresponding parts shown in the various Figures are indicated with the same reference numeral through the Figures. Note that the Figures are not in scale.
The apparatus 1 comprises a frame 1a, a transport assembly 2 configured for displacing the support or tray 7, a film supply assembly 3, an optional film cutting assembly 4, and a packaging assembly 5.
The frame 1a defines the fixed structure supporting the various parts of the apparatus and may include one single fixed structure of a plurality of fixed structures.
The transport assembly 2 is carried by the frame 1a and serves to displace the support or trays 7 along a predefined path. The design of the transport assembly 2 is not particularly relevant to the present invention and any know solution may thus be used. For instance, the transport assembly 2 may comprise a displacement plane 20 (which may be a physical plane where the trays or supports are lying and slide or an ideal plane along which the trays or supports are guided e.g. by means of railways or guides). The plane 20 is defined on a top area of the frame and a conveyor 21 is arranged in correspondence of the plane 20. In the example shown, the transport assembly 2 is carried by, e.g. fixed to, the frame 1a so that the plane 20 is substantially horizontal and the conveyor 21 moves the trays or supports according to the horizontal direction indicated by the arrow A1. The transport assembly 2 is configured for displacing the support or tray along a predefined path from a loading station (not shown), where supports or trays which may already be filled with the respective product(s) P are positioned, to the packaging assembly 5 where a film is tightly fixed to each support or tray, as it will be explained here below in detail. The conveyor 21 displaces the trays or supports, e.g. a prefixed number of trays per time, inside the packaging assembly 5 in proper position for receiving the cut film sheets or in any case a portion of the film. For instance, a control unit 100 (operation of which will be further described herein after) may control the conveyor 21 to displace a prefixed number of trays or supports per time from a region outside the packaging assembly to a region inside the packaging assembly where the tray or supports are in vertical alignment to the film sheets or film portions to which the tray or support need to be sealed. The conveyor 21 may for instance include a first transfer tool (such as a belt), configured for bringing the trays or supports in close proximity to the packaging assembly 5, and a second transfer tool (not shown), adapted to pick one or more of said trays or supports and bring them into the packaging assembly 5. The second transfer tool may for instance include arms acting on the sides of the trays or supports such as to pick the supports from the first transfer tool, bring them into the packaging assembly and then return to the first transfer tool to pick a new set of trays or supports. Alternatively, the conveyor 21 may include pushers (e.g. in the form of bars extending transverse to said direction A1) acting on the trays or supports and pushing them inside the packaging assembly. The pushers may be moved by chains or belts and may be moved into the packaging assembly to properly position a number of trays or supports, and then be retracted from the packaging assembly, once the trays or supports have reached their proper position inside this latter. According to a further alternative, the conveyor 21 may include housings (e.g. in the form of plates or bodies provided with cavities for receiving a number of trays or supports) which are moved along said direction A1 and which are moving inside the packaging assembly together with the supports or trays: according to this last alternative the housings are properly shaped in order to be hosted inside the packaging assembly during the application of the film sheet or film portion to the tray or support. The transport assembly 2 further comprises a motor 22, e.g. a stepping motor unit, for operating the conveyor 21, for example with step-by-step movement. Although several alternatives have been described for conveying the supports or trays into the packaging assembly, any other convenient means adapted to position the supports or trays in the packaging assembly may be used as the specific structure and design of the transport assembly 2 is not relevant to the claimed invention. Note that the products may be positioned on the support or tray 7 either upstream the loading station or in any location between the loading station and the packaging assembly 5. In a further alternative, which is not shown in the drawings, the tray or supports may be online formed: in other words, instead of having a tray loading station, a further film material may be supplied from a further film supply station and fed to a thermoforming tool positioned on the frame 1a and configured for forming the supports or trays. Thermoforming tools are known in the art and are therefore not further described.
The film supply assembly 3 is configured for supplying the film which will then be sealed to the support or trays 7. For instance, the film supply assembly 3 may comprise a film roll 30 which supplies a continuous film 31. The film supplying assembly 3 may further comprise an arm or other structure fixed to the frame 1a and suitable for rotatably supporting the roll 30. Further, the film supplying assembly 3 may comprise film punching devices (not show as per se known) configured essentially to provide the correct profile to the film edges. The punching devices may also help to keep an unrolled portion of film pulled from the film roll aligned according to a prefixed direction. The film supplying assembly 3 may also comprises pinch rollers and/or other means 133 for pulling the film from the roll 10 and properly position it at the cutting assembly 4 (for instance said means may comprise pincers acting on the side of the film and/or pincers acting on the front edge of the film and configured to pull the film). The film rolled on the film roll may be made and have the structure disclosed in the above section dedicated to the film, depending upon the specific need.
The optional film cutting assembly 4 (see
The packaging assembly 5, which is schematically shown in the appended figures, is carried by said frame 1a and is configured for receiving said one or more supports 7 with a product P arranged thereon and for holding a film portion 33 of said film (which may be a portion of a continuous film or a pre-cut film sheet) above a respective of said one or more supports 7, in order to then tightly fixing the film portions to the respective supports. As already mentioned, the packaging assembly includes a lower tool 52 and an upper tool 51. The lower tool 52 comprises a prefixed number of seats 53 for receiving said one or more supports, while the upper tool 51 is configured for holding the film portion 33 above the respective supports when these latter are properly positioned in the seats 53 provided in the lower tool. The upper tool and the lower tool are configured to be movable the one relative to the other between at least a first operating condition (see
For instance, in a non-limiting embodiment, the upper and lower tools when moved to the second operating condition define or contribute to define a packaging chamber 58 (see
Making now reference to
One or more temperature sensors or one or more thermal switches may be positioned in correspondence or in proximity of heater in order to provide the control unit 100 with a feedback signal and allow control of the active surface temperature within the above ranges. In accordance with a preferred aspect, the control unit 100 controls the heating means 55 to keep the active surface at said operating temperature during the whole skin packaging cycle such that as soon as the film touches the active surface 55a it gets immediately and uniformly warmed.
As mentioned, the upper tool 51, and specifically the heater 54, includes holding means 59 for holding the film portion 33 inside the packaging chamber an above the tray or support 7 in said seat 53. In the example shown in the figures, the holding means comprises a plurality of suction apertures 59a leading to the active surface 55a of the heater, at least one vacuum source 59b (e.g. comprising a vacuum pump) controlled by the control unit 100 and connected to the suction apertures, and optionally at least one selector valve 59c, also controlled by the control unit 100, selectively connecting said suction apertures either to said vacuum source or to a vent line 59d. The control unit 100 may be configured to activate the holding means by switching the selector valve to a position where the valve connects the suction apertures to the vacuum source thereby causing suction of gas through the apertures. Alternatively, two valves may be used which may selectively be opened and closed to determine a fluid connection between said apertures either to the vacuum source or to the vent line. Note that in addition or in alternative to vacuum source the holding means may include one or more of the following:
In the embodiment shown in
In the embodiment shown in
In the embodiment shown in
The packaging assembly 5 also includes at least one nozzle 80 provided with a suction aperture 81, and a vacuum arrangement 82 connected to the nozzle 80 and configured to cause suction of air through the nozzle in order to create a desired level of vacuum in the packaging chamber 58 and/or in the volume between the film portion and the support. In practice, the nozzle may be formed or positioned at the end of a tube 84 having an opposite terminal portion connected to the vacuum arrangement 82, which may include at least one vacuum pump 86 controlled by control unit 100. Optionally (see the embodiments of
In practice, the lower tool 52 and the upper tool 51 are configured to receive the film portion 33, hold it in place thanks to the holding means 55 and then position the film portion 33 in a holding position above the respective support 7 located in the seat 53: the nozzle is mounted in the packaging assembly for relative movement with respect to said upper and lower tools in order to position the nozzle as described below. The relative movement of the nozzle may be obtained by actually moving the nozzle (e.g., by means of an actuator 83 carried by the packaging assembly and active on the nozzle) or by moving the upper and lower tools relative to the nozzle (e.g., by means of actuators, not show in the drawings, acting on the upper and lower tools) or by moving the upper and/or lower tools and the nozzle. According to one aspect of the invention, the nozzle 80 is positionable between the bottom surface of the film portion 33 hold by upper tool and the upper surface of the support 7 positioned in a corresponding seat 53 of the lower tool and vertically aligned with said film portion (see
The control unit 100 is configured to control and timely synchronize:
Depending upon the embodiments, when the lower tool and the upper tool are approached the one against the other in the second operating conditions they may define or contribute to define the packaging chamber 58 (
In greater detail, in the embodiments of
In the embodiments of
According to one aspect, the nozzle or at least an external coating applied to the nozzle is made in non-stick material; suitable non-stick materials for example may be: polytetrafluoroethylene (PTFE), anodized aluminum, ceramics, silicone, enameled cast iron, and seasoned cast iron. The above avoids that the nozzle 80—while still inserted in the interspace between the film portion and the support—heat bonds to the support or to the film portion.
After the heat bonding has been completed such that the product is tightly closed against the support, the control unit 100 commands the packaging assembly to remove the nozzle 80 from said interspace 90 by relatively displacing the nozzle with respect to the support. In greater detail, the nozzle 80 (e.g., under the action of said nozzle actuator 83) may be brought between a working condition—where the nozzle is inserted in said interspace 90—and a rest condition—where the nozzle is totally extracted from the interspace 90 and positioned at a prefixed distance from the peripheral border of the support present in the lower tool such as not to interfere with further movement imposed to the formed packaging which needs to be extracted from the packaging assembly.
In summary, once the packaging chamber 58 has been closed and the nozzle 80 has been inserted in the working condition (
In accordance with a possible aspect, which applies to the embodiments where the upper and lower tool may have the ability to form a vacuum chamber 58, a state of vacuum inside the chamber 58 and below the film portion 33 may be created also while keeping the film portion 33 separate from the tray or support 7 while vacuum arrangement 82 is already active. In other words, the control unit 100 may command the packaging assembly 5 (i.e., the holding means 59) to hold the film portion above the respective support (see
The control unit 100 is also configured to then command the removal of the nozzle from said interspace by relatively displacing the nozzle with respect to lower tool and thus with respect to the support present in the lower tool. In a further specific aspect, the control unit 100 may be configured to create a vacuum in the packaging chamber (by controlling the vacuum pump 86 to withdraw gas from said packaging chamber) until a sufficiently low pressure has been reached (e.g. below 100 mbar or below 50 mbar or below 10 mbar), while still holding the film portion attached to the heater. This pressure level is sufficiently low but not too low so that detachment of the film from the heater is avoided (at least during this first phase) as the control unit also creates a pressure level in correspondence of the suction holes or apertures 59a of the holding mean 59, by acting on vacuum source 59b, below the pressure level reached in the packaging chamber. Once a desired state of vacuum is reached inside the chamber 58, the control unit 100 commands the holding means to release the film portion: this may be achieved by commanding selector valve (or valves) to switch the vent line in communication with the suction apertures. The vacuum causes the film to drape down to the tray or support and to form a skin around the product also attaching to the tray or support surface not occupied by the product. At this point the control unit may control again the packaging assembly and lift the upper tool, also causing extraction of the nozzle from the interspace thereby allowing extraction of the packaged product. The cycle described above may then be repeated.
It is noted that in a preferred embodiment the control unit 100 is configured to command the heater 54 to heat the film portion 33 while the same film portion is in its holding position above the support. Furthermore, although the nozzle 80 may be partially extracted from the interspace 90 before the heat bonding 91 is completed, the control unit 100 is preferably configured to cause the nozzle 80 to be completely removed from said interspace only after the heat bonding has air-tightly closed the product between the support and the film portion. In particular, the control unit 100 may be configured to maintain the nozzle 80 in the interspace 90 between the film portion 33 and the support 7 at least until after the upper tool 51 has been moved away from the lower tool 52 and the heater 54 has been separated from the film portion which is being bonded to the support. In an alternative, or additionally, the control unit 100 may be configured to maintain the nozzle 80 in the interspace 90 between the film portion and the support at least until the heater surface facing the film portion is brought to a temperature below the temperature causing heat bonding of the film portion to the support. In this manner, the nozzle is always interposed between the film portion and the support while the film is at a temperature to have heat bonding properties to the support and is only removed once the film has reached a condition where it cannot bond to the support so that at least one film flap 33a (see
In accordance with one aspect of the invention, the lower tool 52 is configured for receiving a support in the shape of a tray comprising a bottom wall 7a and a side wall 7b upwardly extending from said bottom wall. The tray may also include a top flange 7c extending radially outside from the side wall upper portion. In this case, the control unit 100 commands the packaging assembly to position the nozzle 80 in the working condition in the interspace 90, which is defined between a lower surface of the film portion hold by the upper tool and either the flange upper surface (if the tray has a flange) or the upper portion of the side wall of a tray positioned in the lower tool. In particular, the control unit 100 may be configured to command the packaging assembly to position the nozzle—when in the working condition—such that the nozzle radially extends beyond an outer border of the tray flange (in order to be connected to the vacuum arrangement—see
As trays or supports 7 may present a polygonal shape (in a plan view) the lower tool may further be configured to receive a support having a polygonal peripheral border: in case of flat supports a plurality of corner regions are present in the perimeter of the flat support, while in case of trays corner regions are defined either on the top border of the side wall and/or on the flange. In case the support 7 has corner regions, the control unit may configured to command the packaging assembly to position the nozzle 80 in the working condition in an interspace 90 defined at a corner region of the peripheral border of the tray or support positioned in the lower tool.
As already mentioned, in accordance with an aspect of the invention, the lower tool 52 may be configured for receiving a support in the shape of a tray 7 comprising a bottom wall 7a, a side wall 7b upwardly extending from said bottom wall and an optional a top flange 7c extending radially outside from the side wall upper portion. In a variant of this aspect of the invention, the flange 7c or the top portion of the side wall 7b of the tray 7 may include an indent 7d (see
In an alternative (not shown in the drawings), in order to position the nozzle in the working condition, the upper tool comprises a recess configured for receiving said nozzle: in particular, the nozzle cross section presents a profile counter-shaped to the profile of the upper tool recess; in this manner in case of flat supports or of entirely flat flanges the nozzle does not interfere with the support and smoothly positions in the working condition, with the bottom surface of the nozzle being flush to the bottom surface of the heating surface of the heater.
In yet another alternative the upper tool 51 comprises a recess configured for receiving part of said nozzle, while the flange 7c or the top portion of the side wall 7b of the tray 7 may include an indent 7d configured for receiving a bottom part of the same nozzle 80. In other words the nozzle while in working position may be hosted in a seat formed by said recess and/or said indent.
The indent 7d or the recess in the upper tool and thus the nozzle cross section may present a polygonal, e.g. quadrilateral profile. Furthermore, the indent 7d may be located at a corner region of the tray.
The control unit is configured to command the packaging assembly (e.g., the upper and lower tools and the nozzle actuator) to position the nozzle in said interspace either in the indent present in the tray or in the recess present in the upper tool.
Packaging Process
The invention also concerns a packaging process, in particular a vacuum skin packaging process. Exemplary embodiments of the packaging process of the invention are now described which may be for example executed using the apparatus described above or claimed in any one of the appended claims.
In accordance with aspects of the invention, a vacuum skin packaging process comprises the following steps. A support 7 for example of the type described above is provided: the support may be made in a separate apparatus or it may be thermoformed online at a thermoforming station of the apparatus 1. A product P is loaded on the supports at a loading station which may be part of the apparatus or located upstream the apparatus: in any case the loading of the product leaves the support with a free surface, which surrounds the product and which is not contacted by the product; the free surface serves as an area where the film may be bonded to the support. While the supports 7 are provided and moved towards the packaging assembly 5, a film 31 is supplied by the film supply station 3 to the packaging assembly 5. As explained above, the film may be supplied to the packaging assembly as a continuous film or it may be cut into discrete film sheets before reaching the packaging assembly: if the film portion is a discrete piece of film it is preferable that the film portion substantially has the radial size of the support; if a tray with flange is used the film portion in the form of a film sheet shall present the radial size of the tray flange or at least shall be sized enough to have a peripheral border overlapping with the flange all around the tray perimeter. In any case, the process comprises the step of holding at least one film portion 33 above the product loaded support or supports 7 present in the packaging assembly. When the product loaded support 7 and the respective film sheet or film portion 33 have reached the packaging assembly and have been placed in proper vertical alignment, the nozzle 80 is positioned in the interspace 90 between an upper surface of the support and a bottom surface of the film portion, such that the suction aperture 81 of the nozzle may evacuate air from the volume under the film portion and above the support. While the film portion 33 is hold by the upper tool 51 of the packaging assembly in its holding position above the support, the heater 54 provides for heating of the at least one film portion. The process also comprises evacuating air from below the film portion by sucking gas through a suction aperture of the nozzle; evacuation of air may start while the film portion 33 is still hold by the heater 54 (this is possible in those cases where the upper and lower tools form a packaging chamber 58 as described above). Then once a desired level of vacuum has been reached in the packaging chamber or at least in the volume defined between the support and the respective film portion, or after a prefixed time period has lapsed since the start of the evacuation, the film portion is released by the upper tool and in particular by the active surface of the heater. As explained in the apparatus section, when air evacuation takes place the upper and lower tools 51 and 52 may have formed a hermetically closed chamber and/or the film portion has been brought into contact with a peripheral border or band of the underlying support forming a sealing contact with the support and with a portion of the side surface of the nozzle inserted between support and upper tool; furthermore air evacuation may use further channels 85 connected to the vacuum arrangement 82 (see e.g.,
As explained also in the section relating to the detailed description of the apparatus 1, the nozzle 80 is inserted between an upper surface of a peripheral border of the support 7 and a lower surface of a peripheral border of the film portion 33, such that the suction aperture of the nozzle is directed towards a volume comprised between the support and the film portion, but without intruding too much into said volume in order to allow formation of a perfect skin on the product and on the free surface of the support.
In accordance with certain aspects of the invention, it is further noted that the step of evacuating air may take place also while the film portion 33 is in its holding position above the respective product loaded support (see examples of
In accordance with a further aspect of the invention a flap 33a is formed during the packaging process for the easy peel of the film portion 33 and thus for facilitating opening of the vacuum skin package formed with the apparatus and process described above. In greater detail, the nozzle—which is made in a material not sticking or bonding to the film—is kept in the interspace 90 between the film portion and the support while said heat bonding step is taking place and is substantially finished, such that at least one film flap 33a is formed, which is located above said interspace 90 and which does not heat bond to the underlying support 7, thereby forming a grip element for easy opening of the skin package. In further detail, in order to form said flap the nozzle is removed, in particular completely removed, from said interspace after the heater 54 is separated from the film portion, or after the heater surface facing the film portion is brought to a temperature below the temperature causing heat bonding of the film portion to the support.
As described above, air is sucked through the nozzle in order to create the necessary level of vacuum for obtaining a skin package. Once the film portion 33 is heat bonded to the free surface of the support surrounding the product, the process provides for interrupting suction of gas through the nozzle suction aperture 81, and for relatively displacing the nozzle 80 with respect to the support to place the nozzle in a rest condition at a prefixed distance from the peripheral border of the support, while maintaining the suction of air interrupted. In accordance with a possible alternative, extracting of the nozzle 80 from the interspace 90 begins before interrupting suction of gas through said nozzle such that the nozzle continues to suck air at least during an initial phase of its extraction from the interspace.
As mentioned in the above description the process and apparatus of the invention may be used to form a skin package using a tray 7 comprising a bottom wall 7a and a side wall 7b upwardly extending from said bottom wall: in this case is film portion is heat bonded to a free surface of the side wall 7b of the tray (and in certain cases also to a free surface of the base) and forms a heat bonding in the form of a closed annular band 91 extending all around the product which normally rests on and only contacts the base of the tray.
In case the tray comprises a top flange 7c extending radially outside from the side wall upper portion, the interspace 90 is defined between an upper surface of the tray flange 7c and a lower surface of the film portion 33: in this situation, a periphery of the film portion is bonded to upper surface of the flange along the entire perimeter of the flange with the exception of a zone of the flange located at said interspace; this also allows to form at least one film flap 33a not heat bonded to the underlying flange. In case of a tray with a flange 7c, the nozzle is inserted between an upper surface of the tray flange and a lower surface of a peripheral border of the film portion, with the nozzle does and particularly the nozzle distal tip which does extend beyond the inner border of the tray flange. In this way, when the nozzle is in the working condition the suction aperture 81 is substantially flush with the inner surface of the side wall 7b of the tray, thereby not interfering with the drape down movement and the bonding of the film portion 33 to the support 7.
In a further specific variant, the support has a polygonal peripheral border: in this case the process may provide to position the nozzle 80 in an interspace 90 defined at a corner region of the support peripheral border between the upper surface of the support and the bottom surface of the film portion. For example, when the support is a tray with a side wall and a radially protruding top flange, the peripheral border of the flange may be polygonal and the nozzle may be positioned in the interspace defined at a corner region of the flange peripheral border between the upper surface of the flange and the bottom surface of the film portion.
Finally, in accordance with a specific aspect the support may be a tray with a flange (or with top portion of the side wall) having an indent 7d configured for receiving said nozzle: in accordance with a possible embodiment, the indent 7d is formed by a reduction in the height of the side wall, has a constant depth and has an extension along the perimeter of the flange or of the side wall which is at least twice the depth of the indent. In practice the side wall of the tray presents a same height all along its perimeter with the exception of the areas where the indent 7d is formed, said indent having an elongated conformation in a plane parallel to the base of the tray. As the nozzle cross section presents a profile counter-shaped to the profile of the indent, the nozzle cross section takes an elongated conformation and is preferably polygonal, for example rectangular. Moreover, the nozzle suction aperture 81 optionally comprises a plurality of suction orifices regularly distributed at the distal end of the nozzle: for instance the suction orifices may be positioned according to a plurality of parallel lines, which are oriented along the elongation of the cross section. In particular the indent is located at a corner region of the side wall of the tray. It is noted that the flap 33a is formed in correspondence and above the indent 7d.
In accordance with an alternative which may be adopted for flat supports or for trays having no indents the upper tool comprises a recess configured for receiving said nozzle: in detail the nozzle cross section presents a profile counter-shaped to the profile of the upper tool recess, and this latter may be configured to have a constant depth and an extension along an horizontal plane which is at least twice the depth of the recess.
When the nozzle 80 is inserted in the interspace and in particular when the nozzle is sucking air the nozzle is located either in the indent 7d present in the tray or in the recess present in the upper tool, such that in the first case the nozzle top surface remains flush with the top flange or top border of the tray 7 and in the second case the bottom surface of the nozzle remains flush with the active surface of the heater 54. As already mentioned, however, it may be provided that both the tray has an indent and the upper tool has a corresponding recess configured to cooperate in use with the intent of the support to receive the nozzle in the working condition.
Control Unit of Apparatus 1
The apparatus according to the invention has of at least one control unit 100. The control unit (schematically represented in
The control unit may comprise a digital processor (CPU) with memory (or memories), an analogical type circuit, or a combination of one or more digital processing units with one or more analogical processing circuits. In the present description and in the claims it is indicated that the control unit is “configured” or “programmed” to execute certain steps: this may be achieved in practice by any means which allow configuring or programming the control unit. For instance, in case of a control unit comprising one or more CPUs, one or more programs are stored in an appropriate memory: the program or programs containing instructions which, when executed by the control unit, cause the control unit to execute the steps described and/or claimed in connection with the control unit. Alternatively, if the control unit is of an analogical type, then the circuitry of the control unit is designed to include circuitry configured, in use, to process electric signals such as to execute the control unit steps herein disclosed.
The Vacuum Skin Package
The apparatuses and processes described above may be suitable for making a vacuum skin package hosting at least one product, as described above and as claimed in any one of the attached claims.
In particular, according to a specific aspect of the invention and referring to
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and the scope of the appended claims.
Palumbo, Riccardo, Liperoti, Antonio
| Patent | Priority | Assignee | Title |
| Patent | Priority | Assignee | Title |
| 10065755, | May 07 2013 | Cryovac, Inc. | Apparatus and process for packaging a product |
| 10220994, | Oct 19 2012 | Cryovac, LLC | Apparatus and method for vacuum skin packaging of a product |
| 3562058, | |||
| 3950919, | Aug 22 1974 | W R GRACE & CO -CONN, A CORP OF CT | Apparatus and process for vacuum skin packaging |
| 3966045, | May 12 1975 | W R GRACE & CO -CONN, A CORP OF CT | Skin package |
| 4009552, | Jun 25 1974 | Kramer & Grebe GmbH & Co. KG Maschinen-und Modellfabrik | Device for packaging of goods |
| 4030388, | May 14 1976 | E. I. du Pont de Nemours and Company | Film severing method and apparatus |
| 4162599, | Jun 19 1978 | C. A. Pemberton & Co. Limited | Vacuum packaging |
| 4164109, | Oct 24 1977 | Method and device for a tight packing under a thermoplastic and thermoformable film of products requiring an absolute protection | |
| 4870800, | Apr 05 1988 | Nikka Co., Ltd. | Inert gas-filling and sealing device, heat sealing device and packaging apparatus using these devices |
| 4896479, | Jan 31 1987 | E.G.L. Projects Limited | Packaging process |
| 5155974, | Sep 03 1986 | Seawell North America, Inc. | Food packaging with gas between tensioned film & lid |
| 5481852, | Sep 08 1987 | Pakor, Inc. | Method and apparatus to promote gas exchange from a sealed receptacle |
| 6044622, | Jan 11 1999 | CRYOVAC, INC | Method and apparatus for producing a package having a peelable film with a tab to facilitate peeling |
| 6748726, | Oct 06 1997 | Device for packaging products under controlled atmosphere in packages sealed with a film | |
| 6912828, | Feb 24 1999 | HEFESTUS LTD | Packaging method and apparatus |
| 7313900, | Feb 21 2003 | CRYOVAC, INC | Method and apparatus for manufacturing an easy-to-open package |
| 20010011445, | |||
| 20080104930, | |||
| 20120204516, | |||
| DE102006022418, | |||
| FR1139908, | |||
| GB696562, | |||
| JP50106784, |
| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| Mar 02 2017 | Cryovac, LLC | (assignment on the face of the patent) | / |
| Date | Maintenance Fee Events |
| Jul 17 2018 | BIG: Entity status set to Undiscounted (note the period is included in the code). |
| Date | Maintenance Schedule |
| Jul 06 2024 | 4 years fee payment window open |
| Jan 06 2025 | 6 months grace period start (w surcharge) |
| Jul 06 2025 | patent expiry (for year 4) |
| Jul 06 2027 | 2 years to revive unintentionally abandoned end. (for year 4) |
| Jul 06 2028 | 8 years fee payment window open |
| Jan 06 2029 | 6 months grace period start (w surcharge) |
| Jul 06 2029 | patent expiry (for year 8) |
| Jul 06 2031 | 2 years to revive unintentionally abandoned end. (for year 8) |
| Jul 06 2032 | 12 years fee payment window open |
| Jan 06 2033 | 6 months grace period start (w surcharge) |
| Jul 06 2033 | patent expiry (for year 12) |
| Jul 06 2035 | 2 years to revive unintentionally abandoned end. (for year 12) |